Jon E Swenson

Norwegian University of Life Sciences (NMBU) · Department of Ecology and Natural Resource Management (INA)

Large omnivores at the top of food webs play a key role in ecosystems, as their ability to feed on multiple trophic levels stabilizes food-web dynamics and impacts ecosystem functioning. However, it is largely unexplored how large omnivores adapt their trophic interactions to altered resource availability under global change, particularly in terres...

The Swedish brown bear Ursus arctos population is protected, but managed with legally defined hunting seasons. Management decisions (e.g., hunting quotas) are frequently changed and should be based on knowledge about demographic parameters, but collecting sufficient data in the field is time consuming and expensive. An efficient method to collect d...

Background: Despite centuries of research, debate remains on the scaling of metabolic rate to mass especially for intraspecific cases. The high variation of body mass within brown bears presents a unique opportunity to study the intraspecific effects of body mass on physiological variables. The amplitude of metabolic rate reduction in hibernators...

Recreation is a crucial contribution of nature to people, relevant for forest ecosystems. Large carnivores (LCs) are important components of forests, however, their contribution to forest recreational value has not yet been evaluated. Given the current expansion of LC populations, the ongoing forest conservation debate, and the increasing use of na...

Recent comparative studies on fish and mammals have suggested that brain size is associated with cognitive ability, such as problem solving and self-control; larger-brained individuals are assumed to have better cognitive ability. However, it remains largely unexplored whether larger-brained birds perform better in learning and spatial memory tests...

Global climate change has a significant effect on species, as environment conditions change, causing many species’ distributions to shift. During the last three million years, the earth has experienced glacial oscillations, forcing some species to survive in ice-free refugia during glacial periods and then disperse postglacially. In this study, by...

We report the first survey of ecto- and endoparasites of brown bears (Ursus arctos gobiensis) in the Gobi Desert, Mongolia. We collected 40 ticks from 1 female (21 yr old, 48 kg) and 2 males (10 yr, 155 kg; 5 yr, 108 kg) captured for research purposes in May 2018. We found Dermacentor nutalli (n = 35 ticks, 87.5%) on both male bears and Hyalomma as...

Comparing life history traits among populations that have been separated genetically for several hundred thousand years, but live in similar habitats on different continents, may help us understand how ecological and anthropomorphic factors shape life histories. We compared patterns of growth in body length and mass, and the influence of population...

Background The boreal forest is one of the largest biomes on earth, supporting thousands of species. The global climate fluctuations in the Quaternary, especially the ice ages, had a significant influence on the distribution of boreal forest, as well as the divergence and evolution of species inhabiting this biome. To understand the possible effect...

Competition between apex predators can alter the strength of top‐down forcing, yet we know little about the behavioral mechanisms that drive competition in multipredator ecosystems. Interactions between predators can be synergistic (facilitative) or antagonistic (inhibitive), both of which are widespread in nature, vary in strength between species...

Threat to human safety is the most dramatic conflict between humans and large carnivores. Although carnivore attacks are generally rare, bears are relatively often involved. Here, we reveal an association between human encroachment into the landscape, that is, increasing road density, and brown bear-caused human casualties (injuries and fatalities)...

To investigate mechanisms by which hibernators avoid atherogenic hyperlipidemia during hibernation, we assessed lipoprotein and cholesterol metabolisms of free-ranging Scandinavian brown bears (Ursus arctos). In winter- and summer-captured bears, we measured lipoprotein sizes and sub-classes, triglyceride-related plasma-enzyme activities, and muscl...

Muscle atrophy arises from a multiplicity of physio-pathological situations and has very detrimental consequences for the whole body. Although knowledge of muscle atrophy mechanisms keeps growing, there is still no proven treatment to date. This study aimed at identifying new drivers for muscle atrophy resistance. We selected an innovative approach...

Ischemic heart disease remains one of the leading causes of death worldwide. Despite intensive research on the treatment of acute myocardial infarction, no effective therapy has shown clinical success. Therefore, novel therapeutic strategies are required to protect the heart from reperfusion injury. Interestingly, despite physical inactivity during...

Harvest, through its intensity and regulation, often results in selection on female reproductive traits. Changes in female traits can have demographic consequences, as they are fundamental in shaping population dynamics. It is thus imperative to understand and quantify the demographic consequences of changes in female reproductive traits to better...

The effects of human disturbance spread over virtually all ecosystems and ecological communities on Earth. In this review, we focus on the effects of human disturbance on terrestrial apex predators. We summarize their ecological role in nature and how they respond to different sources of human disturbance. Apex predators control their prey and smal...

We report the first survey of ecto-and endoparasites of brown bears (Ursus arctos gobiensis) in the Gobi Desert, Mongolia. We collected 40 ticks from 1 female (21 yr old, 48 kg) and 2 males (10 yr, 155 kg; 5 yr, 108 kg) captured for research purposes in May 2018. We found Dermacentor nutalli (n = 35 ticks, 87.5%) on both male bears and Hyalomma asi...

Enzyme immunoassays (EIAs) are a common tool for measuring steroid hormones in wildlife due to their low cost, commercial availability, and rapid results. Testing technologies improve continuously, sometimes requiring changes in protocols or crucial assay components. Antibody replacement between EIA kits can cause differences in EIA sensitivity, wh...

Harvest can disrupt wildlife populations by removing adults with naturally high survival. This can reshape sociospatial structure, genetic composition, fitness, and potentially affect evolution. Genetic tools can detect changes in local, fine-scale genetic structure (FGS) and assess the interplay between harvest-caused social and FGS in populations...

Large carnivores, such as brown bears (Ursus arctos), wolves (Canis lupus), and tigers (Panthera tigris), can play a key ecological role from their apex position in trophic systems. Within the overall context of bottom-up and top-down regulation of ecosystems, predation by large carnivores often induces demographic and behavioral changes in prey sp...

Humans disturb bears in many ways, either directly when they encounter humans or indirectly by changing their behavior and way of life to avoid humans, human activity, and infrastructure. Here we summarize research on how brown bears normally react when encountering humans, what a human encounter may entail for a bear, and whether bears habituate o...

Bears have fascinated people since ancient times. The relationship between bears and humans dates back thousands of years, during which time we have also competed with bears for shelter and food. In modern times, bears have come under pressure through encroachment on their habitats, climate change, and illegal trade in their body parts, including t...

Bears have fascinated people since ancient times. The relationship between bears and humans dates back thousands of years, during which time we have also competed with bears for shelter and food. In modern times, bears have come under pressure through encroachment on their habitats, climate change, and illegal trade in their body parts, including t...

Bears have fascinated people since ancient times. The relationship between bears and humans dates back thousands of years, during which time we have also competed with bears for shelter and food. In modern times, bears have come under pressure through encroachment on their habitats, climate change, and illegal trade in their body parts, including t...

In small hibernators, global downregulation of the endocannabinoid system (ECS), which is involved in modulating neuronal signaling, feeding behavior, energy metabolism, and circannual rhythms, has been reported to possibly drive physiological adaptation to the hibernating state. In hibernating brown bears (Ursus arctos), we hypothesized that beyon...

The media and scientific literature are increasingly reporting an escalation of large carnivore attacks on humans, mainly in the so-called developed countries, such as Europe and North America. Although large carnivore populations have generally increased in developed countries, increased numbers are not solely responsible for the observed rise in...

The duration of maternal care, an important life history trait affecting population dynamics, varies greatly within species. Yet, our understanding of its predictors is limited, mostly correlative, and subject to misinterpretations, due to difficulties to disentangle the role of maternal‐ and offspring‐related characteristics. We conducted path ana...

Several large carnivore populations are recovering former ranges, and it is important to understand interspecific interactions between overlapping species. In Scandinavia, recent research has reported that brown bear presence influences gray wolf habitat selection and kill rates. Here, we characterized the temporal use of a common prey resource by...

Hibernation is an adaptive strategy to survive harsh winter conditions and food shortage. The use of well‐insulated winter dens helps animals minimize energy loss during hibernation. Brown bears (Ursus arctos ) commonly use excavated dens for hibernation. Physical attributes of excavated dens are expected to impact the bear's heat retention and ene...

Habitat selection of animals depends on factors such as food availability, landscape features, and intra- and interspecific interactions. Individuals can show several behavioral responses to reduce competition for habitat, yet the mechanisms that drive them are poorly understood. This is particularly true for large carnivores, whose fine-scale moni...

Summary of a large ecological quantitative impact assessment for alien species in Norway. Additional information and data repository: Sandvik H et al (2020) Data from: Ecological impact assessments of alien species in Norway. Dryad Digital Repository, https://doi.org/10.5061/dryad.8sf7m0cjc

1 . Due to globalisation, trade and transport, the spread of alien species is increasing dramatically. Some alien species become ecologically harmful by threatening native biota. This can lead to irreversible changes in local biodiversity and ecosystem functioning, and, ultimately, to biotic homogenisation. 2 . We risk‐assessed all alien plants, a...

In small hibernators, global downregulation of the endocannabinoid system (ECS), which is involved in modulating neuronal signaling, feeding behavior, energy metabolism, and circannual rhythms, has been reported to possibly drive physiological adaptation to the hibernating state. We hypothesized that specific changes should occur in hibernating bro...

In small hibernators, global downregulation of the endocannabinoid system (ECS), which is involved in modulating neuronal signaling, feeding behavior, energy metabolism, and circannual rhythms, has been reported to possibly drive physiological adaptation to the hibernating state. In hibernating brown bears ( Ursus arctos ), we hypothesized that bey...

In small hibernators, global downregulation of the endocannabinoid system (ECS), which is involved in modulating neuronal signaling, feeding behavior, energy metabolism, and circannual rhythms, has been reported to possibly drive physiological adaptation to the hibernating state. In hibernating brown bears ( Ursus arctos ), we hypothesized that bey...

[This corrects the article DOI: 10.1371/journal.pone.0225698.].

Life-history theory predicts a trade-off between offspring size and number. However, the role of intra-litter phenotypic variation in shaping this trade-off is often disregarded. We compared the strength of the relationship between litter size and mass from the perspective of the lightest and the heaviest yearling offspring in 110 brown bear litter...

We compiled, summarized and reviewed 338 cases of people killed or injured by brown bears from 1932 to 2017 in Russia, home of about half of the world’s brown bears. During the Soviet period, 1932–1990, hunters and outdoor workers were injured/killed by bears more frequently than people engaged in other activities, 28% and 19% among all incidents,...

Cortisol concentrations in hair are used increasingly as a biomarker of long-term stress in free-ranging wildlife. Cortisol is believed to be integrated into hair primarily during its active growth phase, typically occurring over weeks to months or longer periods, depending on latitude. Cortisol concentrations in hair thus reflect the activity of t...

The ecological requirements of brown bears are poorly known in the Himalaya region, which complicates conservation efforts. We documented the diet of the Himalayan brown bear (Ursus arctos isabellinus) by combining classical scat analysis and a newly developed molecular genetic technique (the trnL approach), in Deosai National Park, Pakistan. Brown...

Hibernation is an adaptive strategy to survive harsh winter conditions and food shortage. The use of well-insulated winter dens helps animals minimize energy loss during hibernation. Brown bears (Ursus arctos) commonly use excavated dens for hibernation. Physical properties of excavated dens, such as the amount of space between a bear and the inner...

Abstract Background Incubating birds must balance the conflict between thermal needs of the developing embryos and their self-maintenance needs for energy. The Chinese Grouse (Tetrastes sewerzowi) lives in high mountain conifer forests and faces energy stress, cold environment, and predation pressure. Females might adjust incubation rhythm to adapt...

In the sexual conflict over the duration of maternal care, male mammals may improve their reproductive success by forcing early mother–offspring separation in species where lactation supresses estrus. However, when individual females benefit from continuing to care for their current offspring, they should adopt counter-strategies to avoid separatio...

We present the results of an inventory and status assessment of alien species in Norway. The inventory covered all known multicellular neobiota, 2496 in total, 1039 of which were classified as naturalised. The latter constitute c. 3% of all species known to be stably reproducing in Norway. These figures are higher than expected from Norway’s latitu...

The understory vegetation of the Eurasian boreal forest is dominated by several ericaceous species (e.g. bilberry Vaccinium myrtillus). These species invest large amounts of energy in their sexual reproduction by producing seed-containing berries, which are apparent adaptations for endozoochory. Their seedlings are, however, almost never found in t...

Hibernating brown bears, Ursus arctos, undergo extended periods of inactivity and yet these large hibernators are resilient to muscle disuse atrophy. Physiological characteristics associated with atrophy resistance in bear muscle have been examined (e.g., muscle mechanics, neural activity) but roles for molecular signaling/regulatory mechanisms in...

Human harvest can induce selection on life history and morphological traits, leading to ecological and evolutionary responses. Our understanding of harvest-induced selection on behavioral traits is, however, very limited. Here, we assessed whether hunters harvest, consciously or not, individuals with specific behavioral traits. We used long-term, d...

Oxidative stress, which is believed to promote muscle atrophy, has been reported to occur in a few hibernators. However, hibernating bears exhibit efficient energy savings and muscle protein sparing, despite long-term physical inactivity and fasting. We hypothesized that the regulation of the oxidant/antioxidant balance and oxidative stress could f...

Knowledge of genetic diversity and population structure is critical for conservation and management planning at the population level within a species' range. Many brown bear populations in Central Asia are small and geographically isolated, yet their phylogeographic relationships, genetic diversity, and contemporary connectivity are poorly understo...

The increasing trend of large carnivore attacks on humans not only raises human safety concerns but may also undermine large carnivore conservation efforts. Although rare, attacks by brown bears Ursus arctos are also on the rise and, although several studies have addressed this issue at local scales, information is lacking on a worldwide scale. Her...

Background In mammals, the hibernating state is characterized by biochemical adjustments, which include metabolic rate depression and a shift in the primary fuel oxidized from carbohydrates to lipids. A number of studies of hibernating species report an upregulation of the levels and/or activity of lipid oxidizing enzymes in muscles during torpor,...

Prior to winter, heterotherms retain polyunsaturated fatty acids (“PUFA”), resulting in enhanced energy savings during hibernation, through deeper and longer torpor bouts. Hibernating bears exhibit a less dramatic reduction (2–5°C) in body temperature, but lower their metabolism to a degree close to that of small hibernators. We determined the lipi...

Degree of unsaturation represented by ratios of different fatty acids groups (“FA ratios”). Fatty acids compositions were determined in white adipose tissue (“WAT”), skeletal muscle (“Muscle”), and blood plasma (“Plasma”) from active (“summer”) and hibernating (“winter”) brown bears. Fatty acids groups are monounsaturated fatty acids (“MUFA”), poly...

Proportions – % of total glycerophospholipids (“GPL”) and sphingolipids (“SL”) – of different groups of GPL and SL. Proportions of ceramide (“Cer”), phosphatidyl-choline (“PC”), phosphatidyl-ethanolamine (“PE”), phosphatidyl-inositol (“PI”), phosphatidyl-serine (“PS”), and sphingomyelin (“SM”) were determined in white adipose tissue (“WAT”), skelet...

Arithmetic means (“Means”) and standard errors (“SE”) of proportions of specific fatty acids (“FA”) among saturated FA, monounsaturated FA or polyunsaturated FA in white adipose tissue (“WAT”), muscle tissue (“Muscle”) and blood plasma (“Plasma”) of bears during the summer active period (“Summer”) and in winter hibernation (“Winter”). Differences o...

Arithmetic means (“Means”) standard errors (“SE”) of concentrations (in mmol l-1) of specific fatty acids among total fatty acids in white adipose tissue (“WAT”), muscle tissue (“Muscle”) and blood plasma (“Plasma”) of bears during the summer active period (“Summer”) and in winter hibernation (“Winter”). Sample sizes used in the linear mixed-effect...

Proportions of triacylglycerides (“TG”) – % of total TG – of different carbon chain lengths, and their respective fatty acid composition. Proportions of different TGs were determined in white adipose tissue (“WAT”), skeletal muscle (“Muscle”), and blood plasma (“Plasma”) of active (“summer”) and hibernating (“winter”) brown bears. Error bars repres...

Abstract Wild animal populations experience selection pressures from both natural and anthropogenic sources. The availability of extensive pedigrees is increasing along with our ability to quantify the heritability and evolvability of phenotypic traits and thus the speed and potential for evolutionary change in wild populations. The environment may...

Several large carnivore populations are increasing in human-dominated landscapes, but this good conservation news includes management challenges. Because of existing fear and negative human attitudes towards carnivores and potential carnivore habituation to people, better knowledge on carnivore behavior is needed to favor human-carnivore coexistenc...

Natal dispersal is an important mechanism for the viability of populations. The influence of local conditions or experience gained in the natal habitat could improve fitness if dispersing individuals settle in an area with similar habitat characteristics. This process, defined as ‘natal habitat-biased dispersal’ (NHBD), has been used to explain dis...

To advance our knowledge on the rubbing behavior of Andean bears (Tremarctos ornatus), we assessed characteristics of their rub-trees in the Peruvian tropical dry forest, where water is a rare and critical resource. We registered characteristics of rubbed and unrubbed trees and shrubs along bear trails in an area of approximately 100 km² surroundin...

Animals adapt their foraging behavior to variations in food availability and predation risk. In Sweden, brown bears (Ursus arctos) depend on a nearly continuous intake of berries, especially bilberries (Vaccinium myrtillus) during late summer and early autumn to fatten up prior to hibernation. This overlaps with the bear hunting season that starts...

Identifying how sympatric species belonging to the same guild coexist is a major question of community ecology and conservation. Habitat segregation between two species might help reduce the effects of interspecific competition and apex predators are of special interest in this context, because their interactions can have consequences for lower tro...

Intraperitoneal radio transmitters have been widely used in free-ranging wild mammals, but there are no long-term studies on their biocompatibility or technical stability within the abdominal cavity of animals. Possible negative health effects may bias results from ecological studies on instrumented animals and raise concerns over animal welfare is...

Human disturbance causes behavioral responses in wildlife, including large carnivores. Previous research in Scandinavia has documented that brown bears (Ursus arctos) show a variety of behavioral reactions to different human activities. We investigated how proximity to human settlements and roads, as proxies of human influence, affected brown bears...

Polyunsaturated fatty acids (PUFAs) exert several important functions across organ systems. During winter, hibernators divert PUFAs from oxidation, retaining them in their tissues and membranes, to ensure proper body functions at low body temperature. PUFAs are also precursors of eicosanoids with pro- and anti-inflammatory properties. This study in...

Reproductive activities can incur various costs to breeding individuals in birds. One cost is that reproduction decreases survival probabilities of attendant individuals, which may have a major effect on population demography. During brood rearing, adults of precocial species usually make extensive movements to lead their young to sites with adequa...

Human persecution and habitat loss have endangered large carnivore populations worldwide, but some are recovering, exacerbating old conflicts. Carnivores can injure and kill people; the most dramatic form of wildlife-human conflict. In Scandinavia, the brown bear (Ursus arctos) population increased from ~500 bears in 1977 to ~3300 in 2008, with an...

Summary from the course “Säkrare björnjakt”. (DOCX)

Background One of the classic approaches in environmental economics is the environmental Kuznets curve, which predicts that when a national economy grows from low to medium levels, threats to biodiversity conservation increase, but they decrease when the economy moves from medium to high. We evaluated this approach by examining how population densi...

Data used in this study. (XLSX)

Muscle atrophy is one of the main characteristics of human ageing and physical inactivity, with resulting adverse health outcomes. To date, there are still no efficient therapeutic strategies for its prevention and/or treatment. However, during hibernation, bears exhibit a unique ability for preserving muscle in conditions where muscle atrophy woul...

As an important extrinsic source of mortality, harvest should select for fast reproduction and accelerated life histories. However, if vulnerability to harvest depends upon female reproductive status, patterns of selectivity could diverge and favor alternative reproductive behaviors. Here, using more than 20 years of detailed data on survival and r...